Re: Summary and Plan for Hot Standby

On Fri, 2009-11-20 at 11:14 +0900, Josh Berkus wrote:
> On 11/15/09 11:07 PM, Heikki Linnakangas wrote:
> > - When replaying b-tree deletions, we currently wait out/cancel all
> > running (read-only) transactions. We take the ultra-conservative stance
> > because we don't know how recent the tuples being deleted are. If we
> > could store a better estimate for latestRemovedXid in the WAL record, we
> > could make that less conservative.
>
> Simon was explaining this issue here at JPUGCon; now that I understand
> it, this specific issue seems like the worst usability issue in HS now.
>  Bad enough to kill its usefulness for users, or even our ability to get
> useful testing data; in an OLTP production database with several hundred
> inserts per second it would result in pretty much never being able to
> get any query which takes longer than a few seconds to complete on the
> slave.

I am pretty sure that OmniTI, PgExperts, EDB and CMD all have customers
that are doing more than that... This sounds pretty significant.

Joshua D. Drake


>
> --Josh Berkus
>
>
>


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